Figure 1
Magnetic compass orientation of zebra finches trained in the ambient RF environment (no RF). (A) Orientation of birds tested under the training condition (no RF; in black). (B) Orientation of birds tested in the presence of a low-intensity 1.4 MHz RF field (RF 1.4low; in red). (C) Orientation of birds tested in the presence of a high-intensity 1.4 MHz RF field (RF 1.4high; in blue). (D) Orientation of birds tested in the presence of a broadband RF field (RF BB; in green). Circular graphs show the orientation of the birds relative to the trained magnetic compass direction, indicated by the triangle on top of the circular graph. Each data point represents the orientation of an individual bird calculated as the vector sum of the time spent in each of the arms of the 4-arm maze during one of the 90 s probe trials. Arrows give the mean direction, with the length proportional to the mean vector length (radius of circle = 1). Double-headed arrows indicate bimodally distributed samples, two double-headed arrows indicate quadrimodally distributed samples. Significant distributions according to the Rayleigh test (P-values < 0.05) are shown with solid arrows and 95% confidence intervals (dotted lines). The mean vector of random distributions with 0.05 ≤ P ≤ 0.2 are shown with dashed arrows; no arrows are shown for totally random distributions with P > 0.2. See Table S2 for detailed statistics. Frequency spectra of the magnetic field intensities b of the RF fields are based on averages over 100 measurements taken at a frequency of 1 kHz, with a resolution bandwidth of 10 kHz. See Table 1 and Methods for more details on the frequency spectra.
